1. Field of the Invention
The present invention relates to an aggregated diamond nanorod, (ADNR), composite for use in rock drilling, machining of wear resistant materials, and other operations which require the high abrasion resistance or wear resistance of a surface formed with a super hard material that also has very high toughness. Specifically, this invention relates to such bodies that include a polycrystalline layer formed from ADNR attached to a cemented carbide substrate via processing at ultrahigh pressures and temperatures.
2. Description of the Art
It is well known in the art to form a polycrystalline diamond cutting element by sintering diamond particles into a compact using a high pressure, high temperature (HP/HT) press and a suitable catalyst sintering aid. Apparatus and techniques to accomplish the necessary sintering of the diamond particles are disclosed in U.S. Pat. No. 2,941,248 to Hall and U.S. Pat. No. 3,141,746 to DeLai.
U.S. Pat. No. 3,745,623 Wentorf et al. teaches sintering of the diamond mass in conjunction with tungsten carbide to produce a composite compact (PDC) in which the diamond particles are bonded directly to each other and to a cemented carbide substrate.
Typically, the diamond used to form a PDC is a mixture of various sizes of synthetic industrial grade diamond single crystals. These diamonds have very high hardness and good abrasion resistance; but lack the ability to resist fracture due to the cleavage planes arising from the well ordered crystallographic orientation of the carbon atoms within the crystal. Thus, wear is caused by micro-fracture of the diamond crystals at the cutting edge of the PDC.
It would be useful if the wear life of a compact could be extended by increasing the fracture toughness of the diamond at the cutting edge on the diamond layer of the PDC.